A brushless DC motor drive system of a capacitorless DC converter

Abstract

The invention discloses a brushless direct current motor driving system for a capacitor-less direct-current converter. The converter is evolved from a conventional Buck converter; and in an evolution process, Buck bus capacitors are removed, and a switch tube is in parallel connection with an inductor so as to provide a continuous current circuit for the inductor at the commutation moment of a motor. The driving system employs a speed and current double closed-loop control manner, and inner and outer loops are controlled by PI regulators. According to the invention, the switch tube is subjected to PWM chopping, and charging and discharging of the inductor are controlled, so that phase currents of the brushless direct current motor are controlled. The driving topology simplifies the pre-stage topology structure of a conventional Buck circuit brushless direct current motor driving system, conventional voltage control is replaced by current control, and the driving topology is suitable for driving the brushless direct current motor whose ideal current waveforms are square waves. Compared with the Buck converter, the converter topology does not need the bus capacitors, so that the cost and size of the driving system are greatly reduced.

Description

Technical field [0001] The invention relates to a brushless DC motor drive system of a capacitorless DC converter, which belongs to the field of DC converter-motor drive. Background technique [0002] The rotor of the brushless DC motor is excited by permanent magnet materials. Due to its small size, high power density, strong dynamic adaptability, and simple control, it has been widely used in various fields of production and life. However, the speed adjustment range of the brushless DC motor under the traditional various PWM control methods is limited by the switching tube frequency of the inverter, and high-frequency PWM chopping will greatly increase the switching loss. [0003] With the development of power electronics technology, Buck circuits are increasingly used in motor speed regulation applications. Controlling the duty cycle of the switch tube can adjust the output voltage of the Buck circuit, which is very suitable for some occasions that require voltage and speed reg...

AI Technical Summary

Problems solved by technology

[0004] However, when the value of the Buck capacitor is small, the voltage oscillation of the Buck bus capacitor during commutation will cause the oscillation of the motor phase current

Moreover, the Buck capacitor is large in size, which cannot reduce the size of the drive system

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